Cognitive wireless communication in which a dynamic spectrum access (DSA) is utilized can be cited as an example of wireless communication. In a cognitive wireless communication system (CRS), a procedure for setting up data communication is as follows. In the cognitive wireless communication system, spectrum sensing is performed to a whole specific wireless frequency domain. Then, a spectrum utilization situation is analyzed based on the spectrum sensing result. A frequency domain (white space) that can be utilized in the data communication of the cognitive wireless communication is fixed based on the analysis result.
In the setup procedure, it is necessary that various pieces of sensing information and sensing control information be exchanged between components of cognitive wireless communication system. At this point, a physical element constituting the cognitive wireless communication system includes a cognitive terminal (CT), a cognitive radio base station (CRB), and a spectrum sensor. The cognitive terminal (CT) and the cognitive radio base station (CRB) can transmit and receive information through a wireless network.
A cognitive pilot channel (CPC) is known as a channel that connects the wireless network (network side) and the cognitive terminal (CT) or the cognitive radio base station (CRB) (terminal side) (for example, see Non-Patent Document 1). The cognitive pilot channel (CPC) is a channel in which the network side and the terminal side are connected over a wide receivable area by utilizing a low frequency band.
It is conceivable that the sensing information and the sensing control information are exchanged on the terminal side (for example, between an in-cognitive-terminal (that is, built-in type) spectrum sensor and a cognitive engine (CE)). It is also conceivable that the sensing information and the sensing control information are exchanged between a stand-alone (that is, independently-operated) spectrum sensor that is spatially divided in the cognitive wireless communication system and another cognitive terminal. The sensing information and the sensing control information are also exchanged between the cognitive radio base stations (CRB), between the cognitive radio base station (CRB) and the cognitive terminal (CT), and between the spectrum sensors. Hereinafter, the channel that is used to exchange the sensing information and the sensing control information between the cognitive terminals (that is, between the terminals that do not exist on the network side) is referred to as an auxiliary control channel for spectrum sensing (ACS).
However, adjacent channel interference is generated in the case that a frequency domain of the cognitive pilot channel (CPC) and a frequency domain of the auxiliary control channel for spectrum sensing (ACS) overlap each other. Particularly, a failure is generated in a dynamic spectrum access when the interference is generated in a cycle in which spectrum sensing is performed. Additionally, competition is generated when the sensing information from the cognitive pilot channel (CPC) and the sensing information from the auxiliary control channel (ACS) simultaneously reach one cognitive terminal (CT).